A record high zT of 2.2 at 740 K is reported in Ge0.92Sb0.08Te single crystals, with an optimal hole carrier concentration ≈4 × 1020 cm−3 that simultaneously maximizes the power factor (PF) ≈56 µW cm−1 K−2 and minimizes the thermal conductivity ≈1.9 Wm−1 K−1. In addition to the presence of herringbone domains and stacking faults, the Ge0.92Sb0.08Te exhibits significant modification to phonon dispersion with an extra phonon excitation around ≈5–6 meV at Γ point of the Brillouin zone as confirmed through inelastic neutron scattering (INS) measurements. Density functional theory (DFT) confirmed this phonon excitation, and predicted another higher energy phonon excitation ≈12–13 meV at W point. These phonon excitations collectively increase the number of phonon decay channels leading to softening of phonon frequencies such that a three‐phonon process is dominant in Ge0.92Sb0.08Te, in contrast to a dominant four‐phonon process in pristine GeTe, highlighting the importance of phonon engineering approaches to improving thermoelectric (TE) performance.

The temperature and concentration distributions of hydrogen in a hot-filament chemical-vapor deposition reactor of diamond have been measured simultaneously by coherent anti-Stokes Raman scattering (CARS). The bright background from the filament was rejected by using CARS and gating on the detector as well as spatial filtering. The CARS spectra provided direct and accurate measurements of the H2 temperature and concentration distributions. The concentration distribution of atomic hydrogen was also determined by assuming a constant pressure condition and equilibrium between translational and rotational degrees of freedom in the system. These temperature and concentration distributions are essential for the understanding and modeling of the diamond growth processes. It was found that the H-atom distribution departed substantially from the thermal equilibrium prediction except very near the filament; however, a diffusion-controlled model predicted the slope of this distribution throughout the measured region.

Prominently enhanced capacitive performance of well-dispersed RuO 2 nanoparticles ͑NPs͒ on nitrogen-containing carbon nanotubes directly grown on Si has been achieved. The function of nitrogen amalgamation is to create preferential sites on carbon nanotubes ͑CNTs͒ with lower interfacial energy for attachment of RuO 2 NPs. This crucial phenomenon leads to a significant improvement of the overall specific capacitance up to the measured scan rate of 2000 mV/s. This work demonstrates that superior electrochemical performances for supercapacitor applications can be achieved with RuO 2 -CNT-based electrodes using nitrogenincorporation technique.

Bioinspired by the composition of the oxygen evolving complex and the fundamental role of calcium for catalysis, we have synthesized calcium–manganese oxides as promising photoelectrodes. We report the first demonstration of hierarchically porous Ca‐containing MnO2 nanorod (NR) bundles as visible‐light‐sensitive photofunctional nanoelectrodes to fundamentally improve the performance of MnO2 for photoelectrochemical hydrogen generation. A substantial amount of Ca (up to 7.8 atom %) can be in situ incorporated into the MnO2 lattice by a simple electroplating technique because of the exceptionally small feature sizes of several nanorods. The maximum photocurrent could be successfully achieved as high as 0.42 mA cm−2, which is the best value for a MnO2 photoanode to date. Significantly, Ca‐containing MnO2 photoanodes illustrated striking photoelectrochemical activity in response to visible light with a high incident photon‐to‐current conversion efficiency of 7 % at a monochromatic wavelength of 450 nm. The improvement in photoactivity of photoelectrochemical response may be attributed to the enhanced visible‐light absorption, increased charge‐carrier densities, and large contact area with electrolyte owing to the synergistic effects of Ca incorporation and specific mesopore networks, thus contributing to photocatalysis. The new design of constructing highly photoactive Ca‐containing MnO2 nanorod bundles sheds light on developing high‐efficiency photoelectrodes for solar hydrogen generation.